Circumference of a Circle

Circumference: Learn

The circumference of a circle is the distance around the outside of
the circle. It could be called the perimeter of the circle.

When you start to learn about circles, you begin to work with the constant
number pi (π), which represents the ratio of the circumference to the
diameter. That is, if you could perfectly measure every circle's diameter
and circumference, then pi is what you get when you divide the circumference
by the diameter.

We can use that idea in reverse to find the circumference when all
we know is the diameter. The value of the number pi is irrational (the decimal has
no pattern and never ends), so we estimate pi by rounding it to 3.14.

How to find the circumference of a circle:

Multiply pi ( π = 3.14 ) by the diameter of the circle.

Example: If a circle has a diameter of 4, its circumference is 3.14*4=12.56